One of the main problems that occur in the use of biodiesel is fuel stability. Some physical properties of biodiesel generally change during storage. Changes in physical and chemical properties are highly correlated with fuel stability and deposit formation. This study was conducted to analyze the effect of B30 biodiesel storage on deposit formation and changes in biodiesel characteristics. Storage Condition is carried out for 3 months in a stainless steel tank. Storage Condition variations are: (1) high relative humidity, (2) moderate relative humidity, (3) low relative humidity. Critical parameters observed were total acid number (TAN), kinematic viscosity, and moisture content measured every 1 month. In addition to observing the characteristics of the formation of biodiesel B30 fuel deposits on each component in the combustion chamber, deposit tests were carried out using the Hot Chamber Deposition Test Rig with variations in plate temperature and chamber used close to the actual engine conditions. The results obtained show that in a period of 3 months there was an increase in mass of fuel deposits with high relative humidity storage conditions, whereas in storage conditions low relative humidity and moderate relative humidity were experiencing a decrease in mass deposit. This is due to the oxidation which is indicated by the growth of organic acids. Whereas in samples with moderate relative humidity and low relative humidity organic acids have not yet emerged. The results of TAN, density, viscosity showed the same tendency, namely an increase though not too large.